This is a fun experiment...
Step one: at night, turn off that gentle light, to dive into that scary darkness.
Step two: camera settings can vary, but I prefer f/22, iso 200. The shutter speed doesn't matter, as long as you have time to press the shutter, run in front of your camera, flash yourself with your brand new flash unit and come back -> approx. 10 to 20 secs.
Step three: enjoy your photograph. ;)
You can also try flashing more than once, and create multiple ghosts.